Grapevine viruses and winemaking potential

Grapevine viruses represent a critical challenge in viticultural districts, significantly undermining vine productivity and longevity. This study investigated the impact of GPGV, GFLV, GLRaV-1, and GLRaV-3 mixed infections on Pinot gris quality attributes in an alpine vineyard. Molecular analysis (ELISA, RT-PCR) highlighted widespread co-infections, likely originating from infected nursery material and vectors. Comparisons between asymptomatic and infected plants revealed severe discrepancies, including an 80% reduction in average bunch weight. Chemical analyses confirmed a profound metabolic shift, characterized by elevated total acidity and depressed sugar levels. The GPGV/GFLV/GLRaV-3 combination proved most detrimental, whereas the GPGV/GFLV/GLRaV-1 co-infection behaved more similarly to the asymptomatic control. Experimental alcoholic fermentation revealed significant differences in maximum fermentation rates (Vmax) and sugar conversion yields under specific viral combinations. Severely affected trials resulted in wines with lower alcohol content and high acidity, confirming that specific co-infections compromise enological suitability. Furthermore, GC-MS/MS analysis verified distinct volatile profiles between infected and asymptomatic samples, driven by alterations in key precursors such as sugars and nitrogenous compounds (YAN). In conclusion, grapevine viruses severely impair vineyard lifespan, productivity, and grape quality, debunking the myth of qualitative improvement via viral infection. While targeted must restoration strategies can mitigate these negative enological effects, strict sanitary control of nursery material remains the primary line of defense